人体组织液定向流动与经络

关于人体经络本质的研究发现了许多新的现象,如在穴位注射放射性核素标记的小分子可观察到物质沿和古人描述的经络差不多的经线迁移,人们不仅得到了这样迁移的图像,而且还测量到了迁移的速度。但对这种循经的物质迁移一直没能从理论上给予解释。通过对人体小腿段胆经和胃经“地”的位置巨微解剖观察发现,经络线位置的骨间膜腓侧和胫侧的血管自上而下呈不均匀分布,在穴位区毛细血管密集,且在穴位和经线上的毛细血管排列呈与经线平行状,根据这一解剖事实,建立了一种毛细血管血浆与组织液交换的血液动力学模型,通过对模型的数值模拟发现,在这样的解剖结构下,组织液能产生一种定向的流动并在毛细血管密集的穴位区获得加速,并不断接力构成一条与经络线相吻合的流线。在这种流线上物质可以定向输运,计算表明在生理状态下这种输运的速度为数厘米至数十厘米每分,这和实验观察到的循经感传速度及放射性核素循经迁移速度相一致。进一步的研究还发现组织压力增高、动脉压改变以及血管壁通透性的变化都会影响流速,这和人体经络的特征是相符合的,为解释经络的科学机理提供了一种新的理论和方法。

Hydrodynamic Comparison of a Semi-submersible,TLP,and Spar:Numerical Study in the South China Sea Environment

The South China Sea contains tremendous oil and gas resources in deepwater areas. However, one of the keys for deepwater exploration, the investigation of deepwater floating platforms, is very inadequate. In this paper, the authors studied and compared the hydrodynamics and global motion behaviors of typical deepwater platforms in the South China Sea environment. The hydrodynamic models of three main types of floating platforms, e.g. the Semi-submersible, tension leg platform （TLP）, and Truss Spar, which could potentially be utilized in the South China Sea, were established by using the 3-D potential theory. Additionally, some important considerations which significantly influence the hydrodynamics were given. The RAOs in frequency domains as well as global motions in time domains under time-varying wind, random waves, and current in 100-y, 10-y, and 1-y return period environment conditions were predicted, compared, and analyzed. The results indicate that the heave and especially the pitch motion of the TLP are favorable. The heave response of the Truss Spar is perfect and comparable with that of the TLP when the peak period of random waves is low. However, the pitch motion of Truss Spar is extraordinarily lar^er than that of Semi-submersible and TLP.

Spacecraft formation control strategy on Sun-Earth Lissajous orbit

To carry out the deep space exploration tasks near Sun-Earth Libration point L2, the CRTBP dynamic model was built up and the numerical conditional quasi-periodic orbit （Lissajons orbit） was computed near L2. Then, a formation controller was designed with linear matrix inequality to overcome the difficuhy of parameter tuning. To meet the demands of formation accuracy and present thruster＇s capability, a threshold scheme was adopted for formation control. Finally, some numerical simulations and analysis were completed to demonstrate the feasibility of the proposed control strategy.

Numerical Simulation of Direct-contact Condensation from a Supersonic Steam Jet in Subcooled Water

The phenomenon of direct-contact condensation,used in steam driven jet injectors,nuclear reactor emergency core cooling systems and direct-contact heat exchangers,was investigated computationally by introducing a thermal equilibrium model for direct-contact condensation of steam in subcooled water.The condensation model presented was a two resistance model which takes care of the heat transfer process on both sides of the interface and uses a variable steam bubble diameter.The injection of supersonic steam jet in subcooled water tank was simulated using the Euler-Euler multiphase flow model of Fluent 6.3 code with the condensation model incorporated. The findings of the computational fluid dynamics（CFD） simulations were compared with the published experimental data and fairly good agreement was observed between the two,thus validating the condensation model.The results of CFD simulations for dimensionless penetration length of steam plume varies from 2.73-7.33,while the condensation heat transfer coefficient varies from 0.75-0.917 MW·（m ^2 ·K）^ -1 for water temperature in the range of 293-343 K.

Numerical Simulation on Ship Bubbly Wake

Based on a volume of fluid two-phase model imbedded in the general computational fluid dynamics code FLUENT6.3.26, the viscous flow with free surface around a model-scaled KRISO container ship （KCS） was first numerically simulated. Then with a rigid-lid-free-surface method, the underwater flow field was computed based on the mixture muitiphase model to simulate the bubbly wake around the KCS hull. The realizable k-e two-equation turbulence model and Reynolds stress model were used to analyze the effects of turbulence model on the ship bubbly wake. The air entrainment model, which is relative to the normal velocity gradient of the free surface, and the solving method were verified by the qualitatively reasonable computed results.

Numerical Simulation of the Flow around Marine Propeller Series

The objective of marine propeller design optimization study is to obtain a propeller with minimum power absorption, maximum efficiency and good materials resistance. In this study, results of numerical simulation carried out on the flow around a conventional marine propeller are presented. The investigation focused on the aspects related to the influence of skew magnitude, thickness and blade number on the propeller performances. First, open water performances of a conventional propeller model DTMB 4148 was estimated using RANS （Reynolds Averaged Navier-Stokes） method. The flow around rotating propeller model was analyzed in the steady state using RANS approach of the commercial CFD （computational fluid dynamics） code fluent. The results provide good agreement with literature data. Numerical results show that the number of blades has an influence on the open water performances of marine propellers. It＇s noticed that the best propeller has four or five blades from only the hydrodynamic aspect. The thickness blade effect has been studied for the same propeller model and compared to the blade with three different thickness values. Results of the calculation show that the blade thickness increases moderately the propeller efficiency. Finally, numerical simulation is performed to study the magnitude skew effect on the propeller blade performance, so three different models were generated. The results of the simulation show that the skew distribution has a positive effect on the open water performances of the marine propellers.

Dynamic model of normal behavior of rock fractures

Based on laboratory tests of artificial fractures in mortar material, established the dynamic constitutive model of normal behaviour of rock fracture,. The tests were systematically conducted under quasi-static and dynamic monotonic loading conditions. The fractures were of different numbers of asperities in contact and were subsequently of different initial contact areas, which imitated the natural rock fractures. The rate of compressive load applied normal to the fractures covers a wide range from 10–1 MPa/s (quasi-static) up to 103 MPa/s (highly dynamic). The normal stress-closure responses of fractures were measured for different loading rates. Based on the stress-closure relation curves measured, a nonlinear (hyperbolic) dynamic model of fracture, normal behaviour, termed as dynamic BB model, was proposed, which was modified from the existing BB model of static normal behaviour of fractures by taking into account the effect of loading rate.

Numerical aerodynamic analysis of bluff bodies at a high Reynolds number with three-dimensional CFD modeling

This paper focuses on numerical simulations of bluff body aerodynamics with three-dimensional CFD(computational fluid dynamics) modeling,where a computational scheme for fluid-structure interactions is implemented.The choice of an appropriate turbulence model for the computational modeling of bluff body aerodynamics using both two-dimensional and three-dimensional CFD numerical simulations is also considered.An efficient mesh control method which employs the mesh deformation technique is proposed to achieve better simulation results.Several long-span deck sections are chosen as examples which were stationary and pitching at a high Reynolds number.With the proposed CFD method and turbulence models,the force coefficients and flutter derivatives thus obtained are compared with the experimental measurement results and computed values completely from commercial software.Finally,a discussion on the effects of oscillation amplitude on the flutter instability of a bluff body is carried out with extended numerical simulations.These numerical analysis results demonstrate that the proposed three-dimensional CFD method,with proper turbulence modeling,has good accuracy and significant benefits for aerodynamic analysis and computational FSI studies of bluff bodies.

Numerical Modeling of Pulverized Coal Combustion at Thermal Power Plant Boilers

The paper deals with development and application the numerical model for solution of processes at combustion chamber of the thermal power plant boiler. Mathematical simulation is based on solution of physical and chemical processes occuring at burning pulverized coal in the furnace model. Three-dimensional flows, heat and mass transfer, chemical kinetics of the processes, effects of thermal radiation are considered. Obtained results give quantitative information on velocity distributions, temperature and concentration profiles of the components, the amount of combustion products including harmful substances. The numerical model becomes a tool for investigation and design of combustion chambers with high-efficiency and reliable operation of boiler at thermal power plants.

Tidal evolution of exo-planetary systems:WASP-50,GJ 1214 and CoRoT-7

We perform numerical simulations to investigate tidal evolution of two single-planet systems, that is, WASP-50 and GJ 1214 and a two-planet system CoRoT-7. The results of orbital evolution show that tidal decay and circularization may play a significant role in shaping their final orbits, which is related to the initial orbital data in the simulations. For GJ 1214 system, different cases of initial eccentricity are also considered as only an upper limit of its eccentricity （0.27） is shown, and the outcome suggests a possible maximum initial eccentricity （0.4） in the adopted dynamical model. Moreover, additional runs with alternative values of dissipation factor Q＇I are carried out to explore tidal evolution for GJ 1214b, and these results further indicate that the real Q＇1 of GJ 1214b may be much larger than its typical value, which may reasonably suggest that GJ 1214b bears a present-day larger eccentricity, undergoing tidal circularization at a slow rate. For the CoRoT-7 system, tidal forces make two planets migrating towards their host star as well as producing tidal circularization, and in this process tidal effects and mutual gravitational interactions are coupled with each other. Various scenarios of the initial eccentricity of the outer planet have also been done to investigate final planetary configuration. Tidal decay arising from stellar tides may still work for each system as the eccentricity decreases to zero, and this is in association with the remaining lifetime of each planet used to predict its future.